Calculating the angle to a location - ios

I have an image of an arrow that behaves like a compass to a specific location. Sometimes it works, and other times it's mirrored. So if I was facing east and the location is directly east of me, it should point up, but sometimes it points down.
#define RADIANS_TO_DEGREES(radians) ((radians) * (180.0 / M_PI))
- (void)locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)heading
{
// update direction of arrow
CGFloat degrees = [self p_calculateAngleBetween:_myLocation
and:_otherLocation];
CGFloat rads = (degrees - heading.trueHeading) * M_PI / 180;
CGAffineTransform tr = CGAffineTransformIdentity;
tr = CGAffineTransformConcat(tr, CGAffineTransformMakeRotation(rads) );
[_directionArrowView setTransform:tr];
}
-(CGFloat) p_calculateAngleBetween:(CLLocationCoordinate2D)coords0 and:(CLLocationCoordinate2D)coords1 {
double x = 0, y = 0 , deg = 0, deltaLon = 0;
deltaLon = coords1.longitude - coords0.longitude;
y = sin(deltaLon) * cos(coords1.latitude);
x = cos(coords0.latitude) * sin(coords1.latitude) - sin(coords0.latitude) * cos(coords1.latitude) * cos(deltaLon);
deg = RADIANS_TO_DEGREES(atan2(y, x));
if(deg < 0)
{
deg = -deg;
}
else
{
deg = 360 - deg;
}
return deg;
}
Is this the correct way to calculate my angle with another location? Or am I missing a step? Being the arrow points directly in the opposite direction sometimes, my assumption is it's an issue with my math.

To calculate radians from x & y:
double r = atan(y/x);
if (x<0)
r = M_PI + r;
else if (x>0 && y<0)
r = 2 * M_PI + r;
There is not issue of dividing by 0 when X is zero because the atan function handles this correctly:
If the argument is positive infinity (negative infinity), +pi/2 (-pi/2) is returned.

Related

Create perpendicular lat long from single cllocation coordinate of X meter

I have user current location i.e. CLLocation Coordinate (location lat & long) and user is on race track pointing to one direction with the help of user current location i created one region now I want some more race track coordinate(say 2m , 4m , 6m away from race track in perpendicular direction) and the track is 10 m long. Please check the image and the red points are on the track.
Please check this image
/**
* Returns the destination point from initial point having travelled the given distance on the
* given initial bearing (bearing normally varies around path followed).
*
* #param {double} distance - Distance travelled, in same units as earth radius (default: metres).
* #param {double} bearing - Initial bearing in degrees from north.
*
* #returns {CLLocationCoordinate} Destination point.
*/
#define kEarthRadius 6378137
- (CLLocationCoordinate2D)destinationPointWithStartingPoint:(MKMapPoint)initialPoint distance:(double)distance andBearing:(double)bearing {
CLLocationCoordinate2D location = MKCoordinateForMapPoint(initialPoint);
double delta = distance / kEarthRadius;
double omega = [self degreesToRadians:bearing];
double phi1 = [self degreesToRadians:location.latitude];
double lambda1 = [self degreesToRadians:location.longitude];
double phi2 = asin(sin(phi1)*cos(delta) + cos(phi1) * sin(delta) * cos(omega));
double x = cos(delta) - sin(phi1) * sin(phi2);
double y = sin(omega) * sin(delta) * cos(phi1);
double lambda2 = lambda1 + atan2(y, x);
return CLLocationCoordinate2DMake([self radiansToDegrees:phi2], ([self radiansToDegrees:lambda2]+540)%360-180);
}
- (CLLocationCoordinate2D)rhumbDestinationPointForInitialPoint:(MKMapPoint)initialPoint distance:(double)distance andBearing:(double)bearing {
CLLocationCoordinate2D location = MKCoordinateForMapPoint(initialPoint);
double delta = distance / kEarthRadius;
double omega = [self degreesToRadians:bearing];
double phi1 = [self degreesToRadians:location.latitude];
double lambda1 = [self degreesToRadians:location.longitude];
double delta_phi = delta * cos(omega);
double phi2 = phi1 + delta_phi;
// check for some daft bugger going past the pole, normalise latitude if so
if (fabs(phi2) > M_PI / 2) {
phi2 = phi2 > 0 ? M_PI-phi2 : -M_PI-phi2;
}
double delta_gamma = log(tan(phi2/2+M_PI/4)/tan(phi1/2+M_PI/4));
double q = fabs(delta_gamma) > 10e-12 ? delta_phi / delta_gamma : cos(phi1);
double delta_lambda = delta*sin(omega)/q;
double lambda2 = lambda1 + delta_lambda;
return CLLocationCoordinate2DMake([self radiansToDegrees:phi2], ([self radiansToDegrees:lambda2]+540)%360-180);
}
- (double)degreesToRadians:(double)degrees {
return degrees * M_PI / 180.0;
}
- (double)radiansToDegrees:(double)radians {
return radians * 180.0 / M_PI;
}
Adapted from : http://www.movable-type.co.uk/scripts/latlong.html
More information on bearing : https://en.wikipedia.org/wiki/Bearing_(navigation)
And rhumb line : https://en.wikipedia.org/wiki/Rhumb_line

Radar like LOVOO app with slider

I am working on an app which has a functionality of RADAR just like LOVOO app. I don't have experience of working on CoreLocation and other location based frameworks.
It would be much appreciated if you could suggest me how should this can be achieved.
What frameworks should i use and how to proceed initially.
Though same question already exists on SO over here my question is same as Radar View like LOVOO but its of no use to me thats why i am asking it again.
What i have tried myself so far is, i have lat and long values of points to plot and i have calculated angle and distance between centre point(my location) and other point
- (float)angletoCoordinate:(CLLocationCoordinate2D)second {
//myCurrentLocation is origin
//second is point
float lat1 = DegreesToRadians(myCurrentLocation.coordinate.latitude);
float lon1 = DegreesToRadians(myCurrentLocation.coordinate.longitude);
float lat2 = DegreesToRadians(second.latitude);
float lon2 = DegreesToRadians(second.longitude);
float dLon = lon2 - lon1;
float y = sin(dLon) * cos(lat2);
float x = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dLon);
float radiansBearing = atan2(y, x);
if(radiansBearing < 0.0)
{
radiansBearing += 2*M_PI;
}
return radiansBearing;
}
-(float)calculateXPointWithLoc:(ARGeoLocation *)loc andDelta:(float)delta{
float angle = radiansToDegrees(delta);
float dpx = (([myCurrentLocation distanceFromLocation:loc.geoLocation])/1000);
if(0<=angle<=90)
return viewRadar.center.x + sin(angle)*dpx ;
else if(90<angle<=180)
return viewRadar.center.x + cos(angle-90)*dpx ;
else if(180<angle<=270)
return viewRadar.center.x - cos(270-angle)*dpx ;
else if(270<angle<360)
return viewRadar.center.x - sin(360-angle)*dpx ;
return 0;
}
-(float)calculateYPointWithLoc:(ARGeoLocation *)loc andDelta:(float)delta{
float angle = radiansToDegrees(delta);
float dpx = (([myCurrentLocation distanceFromLocation:loc.geoLocation])/1000);
if(0<=angle<=90)
return viewRadar.center.y - cos(angle)*dpx ;
else if(90<angle<=180)
return viewRadar.center.y + sin(angle-90)*dpx ;
else if(180<angle<=270)
return viewRadar.center.y + sin(270-angle)*dpx ;
else if(270<angle<360)
return viewRadar.center.y - cos(360-angle)*dpx ;
return 0;
}
and then
int i = 0;
for(ARGeoLocation *loc in coordinates){
deltaAz = [self angletoCoordinate:loc.geoLocation.coordinate];
x = [self calculateXPointWithLoc:loc andDelta:deltaAz];
y = [self calculateYPointWithLoc:loc andDelta:deltaAz];
[[plots objectAtIndex:i] setFrame:CGRectMake(x, y, DIAMETER_PLOT, DIAMETER_PLOT)];
i++;
}
I am not sure whether x and y are correct or not also if they are correct then how can i change these value with change of slider value.
I think the keyword here is Geofencing.
Geofencing is the automatic triggering of an action if your device enters or leaves a certain region. For your case your action is to display the profiles of those users who enter the area of your radar.
Basically you need to calculate a circular region (given a radius) and display all other points within your region.
I once found this tutorial which could teach how to do it by yourself:
http://www.raywenderlich.com/95014/geofencing-ios-swift
I hope it helps!

Calculate distance from a lat/lon coord to a street

I have the coordinates for a street, for example:
CLLocationCoordinate2D street[3];
street[0] = CLLocationCoordinate2DMake(-17.3521, 145.5898);
street[1] = CLLocationCoordinate2DMake(-17.3518, 145.5910);
street[2] = CLLocationCoordinate2DMake(-17.3515, 145.5917);
And a location that is fairly close to the street (about 60 meters):
CLLocationCoordinate2D location = CLLocationCoordinate2DMake(-17.3525, 145.5911);
How can I calculate the distance between the location and position along the street's path?
I'm not looking for the distance to the closest point in the array, I want the distance to the closest position in between the points.
EDIT
It's easier to describe my question with a picture:
street is the three red dots
location is the blue dot
I want to calculate the length of the yellow line in meters.
Take a look at this site: link.
It shows different types of distance measuring with latitude and longitude coordinates and even some code examples (in javascript).
If you have the find the crow distance between two locations, make CLLocation object of two coords, then
CLLocationDistance meters = [newLocation distanceFromLocation:oldLocation];
and if you have find the actual road distance divide the two coords to several coords in straight line and find the distance and add them up.
Here is my attempt to solve this, but I'm not sure if it's the best way?
// http://www.cprogramto.com/c-program-to-find-shortest-distance-between-point-and-line-segment/
double FindDistanceToSegment(double x1, double y1, double x2, double y2, double pointX, double pointY)
{
double diffX = x2 - x1;
float diffY = y2 - y1;
if ((diffX == 0) && (diffY == 0))
{
diffX = pointX - x1;
diffY = pointY - y1;
return sqrt(diffX * diffX + diffY * diffY);
}
float t = ((pointX - x1) * diffX + (pointY - y1) * diffY) / (diffX * diffX + diffY * diffY);
if (t < 0)
{
//point is nearest to the first point i.e x1 and y1
diffX = pointX - x1;
diffY = pointY - y1;
}
else if (t > 1)
{
//point is nearest to the end point i.e x2 and y2
diffX = pointX - x2;
diffY = pointY - y2;
}
else
{
//if perpendicular line intersect the line segment.
diffX = pointX - (x1 + t * diffX);
diffY = pointY - (y1 + t * diffY);
}
//returning shortest distance
return sqrt(diffX * diffX + diffY * diffY);
}
-
CLLocationCoordinate2D street[3];
street[0] = CLLocationCoordinate2DMake(-17.3521, 145.5898);
street[1] = CLLocationCoordinate2DMake(-17.3518, 145.5910);
street[2] = CLLocationCoordinate2DMake(-17.3515, 145.5917);
CLLocationCoordinate2D location = CLLocationCoordinate2DMake(-17.3525, 145.5911);
CLLocationDegrees distanceDegrees = CGFLOAT_MAX;
for (NSUInteger nodeIndex = 1; nodeIndex < 3; nodeIndex++) {
CLLocationCoordinate2D nodeCoord = street[nodeIndex];
CLLocationCoordinate2D prevNodeCoord = street[nodeIndex - 1];
CLLocationDegrees distanceToCurrent = FindDistanceToSegment(prevNodeCoord.longitude, prevNodeCoord.latitude, nodeCoord.longitude, nodeCoord.latitude, location.longitude, location.latitude);
if (distanceToCurrent < distanceDegrees)
distanceDegrees = distanceToCurrent;
}
CLLocationDistance distance = distanceDegrees * 111111; // 1.0 degree is approximately 111,111 meters
NSLog(#"%f", distance); // 78.15 meters

Bilateration with iBeacons

I am trying to use multiple iBeacons to track the user's location in iOS. I know this can be done (somewhat) using 3 beacons and trilateration, but I would like to do it with two (bilateration). I know that I will likely end up with two answers. Does anyone know of a simple way to accomplish this, given the (x,y) location of the beacons (relative to the room), and an averaged RSSI from each beacon?
I have this code for trilateration that I altered to objective-c from javascript:
- (CGPoint)getTrilaterationWithBeacon1:(BBBeacon *)beacon1 Beacon2:(BBBeacon *)beacon2 Beacon3:(BBBeacon *)beacon3 {
float xa = beacon1.x;
float ya = beacon1.y;
float xb = beacon2.x;
float yb = beacon2.y;
float xc = beacon3.x;
float yc = beacon3.y;
float ra = beacon1.distance;
float rb = beacon2.distance;
float rc = beacon3.distance;
float S = (pow(xc, 2.) - pow(xb, 2.) + pow(yc, 2.) - pow(yb, 2.) + pow(rb, 2.) - pow(rc, 2.)) / 2.0;
float T = (pow(xa, 2.) - pow(xb, 2.) + pow(ya, 2.) - pow(yb, 2.) + pow(rb, 2.) - pow(ra, 2.)) / 2.0;
float y = ((T * (xb - xc)) - (S * (xb - xa))) / (((ya - yb) * (xb - xc)) - ((yc - yb) * (xb - xa)));
float x = ((y * (ya - yb)) - T) / (xb - xa);
CGPoint point = CGPointMake(x, y);
return point;
}
So this is the code I ended up using, thanks to ChuckCottrill's suggestion that I look for a formula to calculate intersection of two circles. It is modified from a C version I found online here: http://paulbourke.net/geometry/circlesphere/tvoght.c
The results are somewhat inconsistent due to the inconsistency of the RSSI values returned from the iBeacons.
I will still need to add code to select the correct point somehow (it gives two results).
- (CGPoint)getBilaterationWithBeacon1:(BBBeacon *)beacon1 Beacon2:(BBBeacon *)beacon2 {
float x0 = beacon1.locationX;
float y0 = beacon1.locationY;
float r0 = beacon1.filteredDistance;
float x1 = beacon2.locationX;
float y1 = beacon2.locationY;
float r1 = beacon2.filteredDistance;
float a, dx, dy, d, h, rx, ry;
float x2, y2;
/* dx and dy are the vertical and horizontal distances between
* the circle centers.
*/
dx = x1 - x0;
dy = y1 - y0;
/* Determine the straight-line distance between the centers. */
d = sqrt((dy*dy) + (dx*dx));
/* Check for solvability. */
if (d > (r0 + r1)) {
/* no solution. circles do not intersect. */
return CGPointMake(-1, -1);
}
if (d < abs(r0 - r1)) {
/* no solution. one circle is contained in the other */
return CGPointMake(-1, -1);
}
/* 'point 2' is the point where the line through the circle
* intersection points crosses the line between the circle
* centers.
*/
/* Determine the distance from point 0 to point 2. */
a = ((r0*r0) - (r1*r1) + (d*d)) / (2.0 * d) ;
/* Determine the coordinates of point 2. */
x2 = x0 + (dx * a/d);
y2 = y0 + (dy * a/d);
/* Determine the distance from point 2 to either of the
* intersection points.
*/
h = sqrt((r0*r0) - (a*a));
/* Now determine the offsets of the intersection points from
* point 2.
*/
rx = -dy * (h/d);
ry = dx * (h/d);
/* Determine the absolute intersection points. */
float xi = x2 + rx;
float xi_prime = x2 - rx;
float yi = y2 + ry;
float yi_prime = y2 - ry;
CGPoint point1 = CGPointMake(xi, yi);
CGPoint point2 = CGPointMake(xi_prime, yi_prime);
//pick one
return point2;
}

Different x and y speed (acceleration) in cocos2d?

I want to create a visible object with a trajectory using standard actions (CCMoveBy and e.t.c) which is similar to:
x = sin(y)
My code:
CCMoveBy *moveAction1 = [CCMoveBy actionWithDuration:1.5 position:ccp(300, 0)];
CCEaseInOut *easeInOutAction1 = [CCEaseInOut actionWithAction:moveAction1 rate:2];
CCMoveBy *moveAction2 = [CCMoveBy actionWithDuration:1.5 position:ccp(-300, 0)];
CCEaseInOut *easeInOutAction2 = [CCEaseInOut actionWithAction:moveAction2 rate:2];
CCMoveBy *moveAction3 = [CCMoveBy actionWithDuration:1.5 position:ccp(0, -32)];
CCSpawn *moveActionRight = [CCSpawn actionOne:easeInOutAction1 two:moveAction3];
CCSpawn *moveActionLeft = [CCSpawn actionOne:easeInOutAction2 two:moveAction3];
CCSequence *sequenceOfActions = [CCSequence actionOne:moveActionRight two:moveActionLeft];
CCRepeatForever *finalMoveAction = [CCRepeatForever actionWithAction:sequenceOfActions];
[enemy runAction:finalMoveAction];
This code shows move down only. The problem is that object has a different x and y accelerations and I don't know how to combine them
UPDATED
- (void)tick:(ccTime)dt
{
CGPoint pos = self.position;
pos.y -= 50 * dt;
if (pos.y < activationDistance) {
pos.x = 240 + sin(angle) * 140;
angle += dt * 360 * 0.007;
if (angle >= 360) {
angle = ((int)angle) % 360;
}
}
self.position = pos;
}
It is my current solution. I can increase activationDistance to adjust the object trajectory. But I want to setup an initial value of the angle variable.
I use numbers instead of variables because they are used inside this function only.
SOLVED
To change the initial angle:
angle = point.x < 240 ? -asin((240 - point.x) / 140) : asin((point.x - 240) / 140);
the main problem was my tiled map has its own coordinates and cover 320x320 part of the screen only
I think it will be easier for you to just do it in your frame update method (the one I assume you schedule for updating your objects. So why not just do :
- (void)tick:(ccTime)dt {
CGPoint pos = myObject.position;
pos.x = <desired x> + sin(angle);
pos.y = pos.y - y_acceleration * dt;
angle += dt * 360 * x_acceleration;
if (angle >= 360)
angle = ((int)angle) % 360;
myObject.position = pos;
}
And you can apply the same for the y axis of the object

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